Interruption in a linux multithreaded app generate SIGSEGV - c++

Question

I have a x86_64 multithreaded application where I try to emulate avr interrupts: when interrupt occurs application and all threads are suspended while interrupt handler execute defined actions.
I thought signals were the solution to do this so I'm trying to catch SIGUSR1 signal, but when I raise SIGUSR1 program exit with a segmentation fault error before executing apply function. (I have tried mutex in isr and signals but removed as actually they run in the main thread)
The code is within 5 files.
isr.h
#ifndef __ISR_H__
#define __ISR_H__
typedef void (*routine_t)(void);
class InterruptServiceRoutine
{
routine_t routine;
bool locked = true;
public:
InterruptServiceRoutine(routine_t isr);
void apply();
void unlock(){locked = false;};
};
typedef InterruptServiceRoutine ISR_t;
#endif // __ISR_H__
isr.cpp:
#include <ISR.h>
InterruptServiceRoutine::InterruptServiceRoutine(routine_t isr): routine(isr){}
void InterruptServiceRoutine::apply()
{
if (!locked) routine();
}
Signals.h:
#ifndef __SIGNALS_H__
#define __SIGNALS_H__
#include <vector>
#include <ISR.h>
#include <signal.h>
class Logger;
class Signals
{
private:
Logger& log;
std::vector<ISR_t*> isr_table;
public:
Signals(Logger&);
~Signals();
unsigned int count(void);
void clear(void);
void connect(ISR_t &isr);
void apply(int);
};
#endif // __SIGNALS_H__
Signals.cpp:
#include <signal.h>
#include <pthread.h>
#include <functional>
#include <ISR.h>
#include <Signals.h>
#include <Logger.h>
using namespace std;
void Signals::apply(int)
{
sigset_t sigs_to_block;
sigfillset(&sigs_to_block);
pthread_sigmask(SIG_BLOCK, &sigs_to_block, NULL);
unsigned int num_interrupts = count();
for (unsigned int i=0; i < num_interrupts; ++i)
{
isr_table[i]->apply();
}
pthread_sigmask(SIG_SETMASK, NULL, NULL);
}
Signals::Signals(Logger& _log): log(_log)
{
clear();
auto _apply = bind1st(mem_fun(&Signals::apply), this);
struct sigaction new_action;
new_action.sa_handler = (__sighandler_t) &_apply;
new_action.sa_flags = 0;
sigfillset(&new_action.sa_mask);
sigaction(SIGUSR1, &new_action, NULL);
pthread_sigmask(SIG_SETMASK, NULL, NULL);
}
Signals::~Signals() {
struct sigaction new_action;
new_action.sa_handler = SIG_DFL;
new_action.sa_flags = 0;
sigemptyset(&new_action.sa_mask);
sigaddset(&new_action.sa_mask, SIGUSR1);
sigaction(SIGUSR1, &new_action, NULL);
clear();
}
void Signals::clear(void)
{
isr_table.clear();
isr_table.reserve(20);
}
unsigned int Signals::count(void)
{
return isr_table.size();
}
void Signals::connect(ISR_t &isr)
{
isr_table.push_back(&isr);
}
SignalsTest.test:
#include <signal.h>
#include <pthread.h>
#include <cxxtest/TestSuite.h>
#include <ISR.h>
#include <Signals.h>
#include <Logger.h>
volatile sig_atomic_t isr_called_count;
void isr(void)
{
++isr_called_count;
}
class SignalsTestSuite: public CxxTest::TestSuite
{
Logger log;
Signals handler;
public:
SignalsTestSuite(void): handler(log){}
void setUp()
{
handler.clear();
isr_called_count = 0;
}
/* ... truncated for more visibility ... */
void testWhenRaiseSIGUSRItCallsAvailableRoutine(void)
{
ISR_t routine(&isr);
routine.unlock();
handler.connect(routine);
handler.connect(routine);
raise(SIGUSR1);
TS_ASSERT_EQUALS(isr_called_count, 2);
}
};
Debug informations:
GNU gdb (Gentoo 7.7.1 p1) 7.7.1
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://bugs.gentoo.org/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./out/signals...done.
(gdb) r
Starting program: test/out/signals
warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Running 3 tests..
Program received signal SIGUSR1, User defined signal 1.
0x00007ffff7bd0beb in raise (sig=10) at ../sysdeps/unix/sysv/linux/pt-raise.c:36
36 return INLINE_SYSCALL (tgkill, 3, pid, THREAD_GETMEM (THREAD_SELF, tid),
(gdb) bt
#0 0x00007ffff7bd0beb in raise (sig=10) at ../sysdeps/unix/sysv/linux/pt-raise.c:36
#1 0x0000000000403f38 in SignalsTestSuite::testWhenRaiseSIGUSRItCallsAvailableRoutine (this=this#entry=0x631cc0 <suite_SignalsTestSuite>)
at test/SignalsTest.test:62
#2 0x0000000000403f92 in TestDescription_suite_SignalsTestSuite_testWhenRaiseSIGUSRItCallsAvailableRoutine::runTest (this=<optimized out>) at out/signals.cpp:38
#3 0x000000000040424e in CxxTest::RealTestDescription::run (this=<optimized out>) at /opt/cxxtest/cxxtest/RealDescriptions.cpp:109
#4 0x0000000000409afb in CxxTest::TestRunner::runTest (this=this#entry=0x7fffffffd29f, td=...) at /opt/cxxtest/cxxtest/TestRunner.h:85
#5 0x0000000000409c76 in CxxTest::TestRunner::runSuite (this=this#entry=0x7fffffffd29f, sd=...) at /opt/cxxtest/cxxtest/TestRunner.h:72
#6 0x0000000000409e15 in CxxTest::TestRunner::runWorld (this=this#entry=0x7fffffffd29f) at /opt/cxxtest/cxxtest/TestRunner.h:57
#7 0x0000000000409f52 in CxxTest::TestRunner::runAllTests (listener=...) at /opt/cxxtest/cxxtest/TestRunner.h:34
#8 0x0000000000409f93 in CxxTest::ErrorFormatter::run (this=this#entry=0x7fffffffd320) at /opt/cxxtest/cxxtest/ErrorFormatter.h:59
#9 0x000000000040aa89 in CxxTest::Main<CxxTest::ErrorPrinter> (tmp=..., argc=argc#entry=1, argv=argv#entry=0x7fffffffd448) at /opt/cxxtest/cxxtest/TestMain.h:109
#10 0x0000000000407f62 in main (argc=1, argv=0x7fffffffd448) at out/runner.cpp:18
(gdb) l
31 that. */
32 pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
33 if (__glibc_unlikely (pid < 0))
34 pid = -pid;
35
36 return INLINE_SYSCALL (tgkill, 3, pid, THREAD_GETMEM (THREAD_SELF, tid),
37 sig);
38 }
(gdb) s
Program received signal SIGSEGV, Segmentation fault.
0x00007fffffffd210 in ?? ()
(gdb) bt
#0 0x00007fffffffd210 in ?? ()
#1 <signal handler called>
#2 0x00007ffff7bd0beb in raise (sig=10) at ../sysdeps/unix/sysv/linux/pt-raise.c:36
#3 0x0000000000403f38 in SignalsTestSuite::testWhenRaiseSIGUSRItCallsAvailableRoutine (this=this#entry=0x631cc0 <suite_SignalsTestSuite>)
at test/SignalsTest.test:62
#4 0x0000000000403f92 in TestDescription_suite_SignalsTestSuite_testWhenRaiseSIGUSRItCallsAvailableRoutine::runTest (this=<optimized out>) at out/signals.cpp:38
#5 0x000000000040424e in CxxTest::RealTestDescription::run (this=<optimized out>) at /opt/cxxtest/cxxtest/RealDescriptions.cpp:109
#6 0x0000000000409afb in CxxTest::TestRunner::runTest (this=this#entry=0x7fffffffd29f, td=...) at /opt/cxxtest/cxxtest/TestRunner.h:85
#7 0x0000000000409c76 in CxxTest::TestRunner::runSuite (this=this#entry=0x7fffffffd29f, sd=...) at /opt/cxxtest/cxxtest/TestRunner.h:72
#8 0x0000000000409e15 in CxxTest::TestRunner::runWorld (this=this#entry=0x7fffffffd29f) at /opt/cxxtest/cxxtest/TestRunner.h:57
#9 0x0000000000409f52 in CxxTest::TestRunner::runAllTests (listener=...) at /opt/cxxtest/cxxtest/TestRunner.h:34
#10 0x0000000000409f93 in CxxTest::ErrorFormatter::run (this=this#entry=0x7fffffffd320) at /opt/cxxtest/cxxtest/ErrorFormatter.h:59
#11 0x000000000040aa89 in CxxTest::Main<CxxTest::ErrorPrinter> (tmp=..., argc=argc#entry=1, argv=argv#entry=0x7fffffffd448) at /opt/cxxtest/cxxtest/TestMain.h:109
#12 0x0000000000407f62 in main (argc=1, argv=0x7fffffffd448) at out/runner.cpp:18
(gdb) l
Line number 39 out of range; ../sysdeps/unix/sysv/linux/pt-raise.c has 38 lines.
(gdb) s
Cannot find bounds of current function
(gdb) c
Continuing.
Program terminated with signal SIGSEGV, Segmentation fault.
The program no longer exists.
Memory informations:
$ valgrind --leak-check=full --show-leak-kinds=all ./out/signals
==31715== Memcheck, a memory error detector
==31715== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==31715== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==31715== Command: ./out/signals
==31715==
Running 3 tests..==31715==
==31715== Process terminating with default action of signal 11 (SIGSEGV)
==31715== Bad permissions for mapped region at address 0xFFEFFF1F0
==31715== at 0xFFEFFF1F0: ???
==31715== by 0x409F92FF: ???
==31715== by 0xFFF: ???
==31715== by 0x40AA88FF: ???
==31715==
==31715== HEAP SUMMARY:
==31715== in use at exit: 176 bytes in 2 blocks
==31715== total heap usage: 2 allocs, 0 frees, 176 bytes allocated
==31715==
==31715== 16 bytes in 1 blocks are still reachable in loss record 1 of 2
==31715== at 0x4C294C0: operator new(unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==31715== by 0x408AB1: CxxTest::ErrorPrinter::ErrorPrinter(std::ostream&, char const*, char const*) (ErrorPrinter.h:43)
==31715== by 0x407F4C: main (runner.cpp:17)
==31715==
==31715== 160 bytes in 1 blocks are still reachable in loss record 2 of 2
==31715== at 0x4C294C0: operator new(unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==31715== by 0x40B2E3: __gnu_cxx::new_allocator<InterruptServiceRoutine*>::allocate(unsigned long, void const*) (new_allocator.h:104)
==31715== by 0x40B315: std::_Vector_base<InterruptServiceRoutine*, std::allocator<InterruptServiceRoutine*> >::_M_allocate(unsigned long) (in test/out/signals)
==31715== by 0x40B941: InterruptServiceRoutine** std::vector<InterruptServiceRoutine*, std::allocator<InterruptServiceRoutine*> >::_M_allocate_and_copy<std::move_iterator<InterruptServiceRoutine**> >(unsigned long, std::move_iterator<InterruptServiceRoutine**>, std::move_iterator<InterruptServiceRoutine**>) (stl_vector.h:1138)
==31715== by 0x40BA28: std::vector<InterruptServiceRoutine*, std::allocator<InterruptServiceRoutine*> >::reserve(unsigned long) (vector.tcc:75)
==31715== by 0x40AE7D: Signals::clear() (Signals.cpp:57)
==31715== by 0x40AF50: Signals::Signals(Logger&) (Signals.cpp:32)
==31715== by 0x403531: SignalsTestSuite::SignalsTestSuite() (in test/out/signals)
==31715== by 0x40302D: __static_initialization_and_destruction_0(int, int) (signals.cpp:18)
==31715== by 0x403144: _GLOBAL__sub_I_suite_SignalsTestSuite_init (signals.cpp:39)
==31715== by 0x4147EC: __libc_csu_init (elf-init.c:88)
==31715== by 0x5A8DA34: (below main) (libc-start.c:245)
==31715==
==31715== LEAK SUMMARY:
==31715== definitely lost: 0 bytes in 0 blocks
==31715== indirectly lost: 0 bytes in 0 blocks
==31715== possibly lost: 0 bytes in 0 blocks
==31715== still reachable: 176 bytes in 2 blocks
==31715== suppressed: 0 bytes in 0 blocks
==31715==
==31715== For counts of detected and suppressed errors, rerun with: -v
==31715== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Erreur de segmentation
I've tried to figure out why there are missing symbols (0x00007fffffffd210 in ?? () and at 0xFFEFFF1F0: ??? ...):
(gdb) info share
From To Syms Read Shared Object Library
0x00007ffff7ddca80 0x00007ffff7df5960 Yes /lib64/ld-linux-x86-64.so.2
No linux-vdso.so.1
0x00007ffff7bc6a40 0x00007ffff7bd2781 Yes /lib64/libpthread.so.0
0x00007ffff79bb360 0x00007ffff79be0dc Yes /lib64/librt.so.1
0x00007ffff770f5f0 0x00007ffff77733c3 Yes /usr/lib/gcc/x86_64-pc-linux-gnu/4.8.4/libstdc++.so.6
0x00007ffff73c04f0 0x00007ffff7425266 Yes /lib64/libm.so.6
0x00007ffff71a7ac0 0x00007ffff71b6e45 Yes /usr/lib/gcc/x86_64-pc-linux-gnu/4.8.4/libgcc_s.so.1
0x00007ffff6e2c430 0x00007ffff6f53b44 Yes /lib64/libc.so.6
But can't find a way to get "linux-vdso.so.1" on gentoo.
I'm a beginner in C++ what I'm doing wrong with memory ?
Have you a tip to fix this ?
Edit1:
routine_t and __sighandler_t types are aliases for: void (*)(void)

Answer 1

I believe that you can safely ignore the error. A StackOverflow member with a reputation in the top 0.25% of members (!) says that this warning "Could not load shared library symbols for linux-vdso.so.1." is something you can safely ignore. To see the post, go here:
Could not load shared library symbols for linux-vdso.so.1. while debugging

Answer 2

Problem solved thanks to Igor Tandetnik.
Finally the following code function.
signals.h:
#ifndef __SIGNALS_H__
#define __SIGNALS_H__
#include <vector>
#include <ISR.h>
#include <signal.h>
using namespace std;
class Logger;
class Signals
{
private:
Logger& log;
static bool action_handled;
void reserve();
public:
static void start();
static void stop();
static std::vector<ISR_t*> isr_table;
Signals(Logger& _log);
~Signals();
unsigned int count(void);
void clear(void);
void connect(ISR_t&);
static void apply(int);
static void unmask_pthread_signals();
static void mask_pthread_signals();
};
#endif // __SIGNALS_H__
signals.cpp:
#include <functional>
#include <signal.h>
#include <pthread.h>
#include <ISR.h>
#include <Signals.h>
#include <Logger.h>
using namespace std;
vector<ISR_t*> Signals::isr_table={};
bool Signals::action_handled=false;
void Signals::apply(int)
{
mask_pthread_signals();
for (unsigned int i=0; i < isr_table.size(); ++i)
{
isr_table[i]->apply();
}
unmask_pthread_signals();
}
Signals::Signals(Logger& _log): log(_log){
clear();
start();
}
Signals::~Signals() {
clear();
stop();
}
void Signals::clear(void)
{
isr_table.clear();
isr_table.reserve(0);
}
unsigned int Signals::count(void)
{
return isr_table.size();
}
void Signals::start()
{
if (action_handled) return;
struct sigaction new_action;
new_action.sa_handler = (__sighandler_t) &Signals::apply;
new_action.sa_flags = 0;
sigemptyset(&new_action.sa_mask);
sigaction(SIGUSR1, &new_action, NULL);
unmask_pthread_signals();
action_handled = true;
}
void Signals::stop()
{
if (!action_handled) return;
struct sigaction new_action;
new_action.sa_handler = SIG_DFL;
sigemptyset(&new_action.sa_mask);
sigaction(SIGUSR1, &new_action, NULL);
mask_pthread_signals();
action_handled = false;
}
void Signals::unmask_pthread_signals()
{
sigset_t signals_mask;
sigemptyset(&signals_mask);
pthread_sigmask(SIG_SETMASK, &signals_mask, NULL);
}
void Signals::mask_pthread_signals()
{
sigset_t signals_mask;
sigfillset(&signals_mask);
pthread_sigmask(SIG_SETMASK, &signals_mask, NULL);
}
void Signals::reserve()
{
if (isr_table.capacity() <= isr_table.size()) {
isr_table.reserve(isr_table.capacity() + 20);
}
}
void Signals::connect(ISR_t &isr)
{
start();
reserve();
isr_table.push_back(&isr);
}